The present invention relates to a disposable or expendable protective mask which is simple, lightweight and inexpensive, yet effective for protecting the wearer's respiratory system and eyes from the effects of toxic gases and other harmful substances. More specifically, the present invention comprises a protective mask formed from a porous, non-woven sheet material consisting essentially of glass fibers, and a suitable binding agent. The sheet material serves to filter the air of noxious agents, including sub-micron sized particulate matter. The sheet material may optionally include a gas adsorbent substance in an amount sufficient to remove toxic gases from the inhaled air.
Protective masks are widely used by the military and in industry, e.g. in chemical processing plants and in mining operations where noxious fumes may occur. Conventional gas masks generally consist of a face piece equipped with a canister for filtering and adsorbing gas from inhaled air and straps for attaching the mask to the wearer's head. One or more outlet valves are also provided for discharging exhaled air. The face piece is designed to form a gas-tight seal around the wearer's face, in order to ensure that only air that has been passed through the canister is inhaled.
Prior art gas masks generally accomplish removal of noxious substances from the inhaled air by a combination of physical and chemical means. Particulate matter or droplets suspended in the air are removed by mechanical filtering using a fibrous filter media made, for example, from asbestos, cellulose or glass fibers. Gases or vapors are removed by adsorption on surface-active materials having high retention capacity, such as activated carbon. Various chemical agents may be employed to eliminate specific gases or fumes by formation of chemical compounds, e.g. alkalies for the removal of acid fumes, heavy metal-containing compounds for the removal of ammonia, and copper salts for the removal of hydrocyanic acid.
Although satisfactory in many respects, prior art gas masks of the type described above are not without certain shortcomings. For example, the prior art masks tend to be ineffective in removing sub-micron sized particles from the inhaled air. In this connection, there is concern that such masks would provide inadequate protection against the newer generations of chemical and biological warfare agents which are released in atomized form and have particle sizes as small as 0.3 microns. Furthermore, the prior art gas masks are quite expensive to manufacture, and, being a relatively sophisticated piece of equipment, require considerable familiarity and practice on the part of the wearer in order to be used effectively. Such factors have prevented gas masks from being made available to the general population for facilitating escape from fires. It is well-documented that the vast majority of fire-related deaths do not result from burns, but are due to the inhalation of smoke and toxic gases, as many fatalities occur in areas far removed from the actual fire scene, particularly in public buildings, such as hotels, theaters and night clubs.